Components which are used at high temperatures often have protective layers protecting the component against corrosion or excessive introduction of heat.
However, the layer may flake off or degrade while the component is in use, with the result that the desired protection function can no longer be provided. This leads to damage to the substrate and sometimes to component failure. In the event of damage to the substrate, it may no longer be possible to refurbish the component, i.e. to recoat it with a new layer.
EP 1 318 273 A2, EP 1 375 825 A1 and U.S. Pat. No. 6,039,537 disclose a turbine blade or vane in which a film cooling hole is closed by a single layer. EP 1 318 273 A2 also describes the presence of a plug in the film cooling hole even after coating.